置换检验，对小样本最实用的检验方法，原理是通过样本随机的选择而形成很多数据集合，简单易学，初学者适用。permatution tes在实验最后的检验过程中经常用到。-Permutation test on a small sample of the most useful test method, the principle of random selection through the sample to form a lot of data collection, easy to learn